1. Field of the Invention
The present invention relates to backpacks for SCUBA divers for mounting air tanks on the back of the diver during an underwater dive. More particularly, it relates to an improved backpack which is soft and of malleable construction in order to more comfortably cushion the weight and configuration of the air tank on the diver's back.
2. Description of the Prior Art
Backpacks for SCUBA diver air tanks are in most cases a rigid plastic board which can be strapped onto the back of a diver or secured to a diver's over garment such as a jacket or buoyancy compensator. A typical buoyancy compensator and air tank backpack are described in U.S. Pat. No. 4,694,772 for Diver's Buoyancy Compensator Belt, column 3, lines 15-29. The problem with the molded plastic backpack is that it is quite uncomfortable and can become particularly burdensome and tiring on extended dives.
Prior to the present invention, only cloth, fabric, metal, plastic, or a combination of the above materials have been utilized to make backpacks to hold SCUBA diver gas breathing tanks, hereafter called air tanks. The fabric and cloth backpacks experience four different types of problems. First, the tank can shift its position on the back of the diver due to stretch of the material or a poor fit or configuration of the backpack on the diver. The movement of the backpack can be very irritating or cause discomfort, particularly if it allows the tank to hit the diver's head, or if it allows the tank to roll from side to side on a diver's back throughout the duration of the dive. A second problem is that the padding, which is provided around the shoulders of the diver and the tank, can cause buoyancy problems and upward lift which are generally compounded as the thickness of the padding is increased for effectiveness and comfort. To counter the lift, the diver has to wear more lead on the weight belt to offset the buoyancy increase. This requires the diver to transport more weight to the dive site and to wear more weight underwater which is uncomfortable. The increase in discomfort is quite proportional to the increase in weight. Third, the variety of different shapes of divers' backs are a major problem to fit a universal backpack in order to provide a universally good fit. A diver's back can be long or short, wide or narrow, and the spine can be deeply curved or straight. In order to accommodate these various configurations, a fabric backpack will usually be loose on most divers at some location or another. Fourth, in these backpacks padded with foam rubber, an especially troublesome physical transformation occurs: the foam rubber compresses as the diver descends in the water. As the padding compresses, the fit of the backpack becomes looser. For example, at 33 feet of depth in water, typical foam rubber is compressed to one half its volume. The average dive is 60 feet and the compression of the foam rubber is considerably greater at that depth.
The metal, plastic, or rigid construction backpacks for holding SCUBA tanks likewise have problems of fit and comfort. Rigid backpacks do not fit the different shapes and diver back sizes for the same reasons. While fabric and cloth backpacks can be provided with padding which causes lift, rigid backpacks can eliminate lift but have a fixed configuration which is to some degree in all cases unpadded and uncomfortable. This can cause diver discomfort when tightening the tank to the necessary degree to prevent movement on his back, and there can be increased and considerable discomfort over the duration of a dive if the backpack can move or if it is so tight that it causes cramping of the body. Thus, a more comfortable backpack for SCUBA diver air tanks is required to permit relaxed, more pleasant, and extended dives.